MELEACH-L proposed in this paper as an expanded version of MELEACH makes the major functions of MELEACH applicable to large-scale WSNs whose dimension is much larger than the largest transmission radius of the sensor nodes. The channel assignment among neighbor clusters and the cooperation among cluster heads during data collection are two major difficulties in a large WSN. MELEACH-L solves the two problems separately by controlling the size of each cluster and separating cluster heads from backbone nodes. According to our analysis and simulations, these two techniques solve the problems satisfactorily efficiently, making MELEACH-L an applicable version of MELEACH for large-scale WSNs.